Caracterização ambiental e associações entre solos e macaubais de ocorrência espontânea em Bambuí/MG

The macauba palm (Acrocomia aculeata) presents promising potential for the production of biodiesel and it is in the initial stage of domestication. Considering the spontaneous occurrence of this palm tree in a large part of the Brazilian territory and the possibility of commercial exploitation of its products and co-products, this work aimed to characterize the spontaneous occurrence of macauba palm within the area of the river basin of the river Perdição, belonging to the municipality of Bambuí-MG, investigating the associations between the soils and the phytosociological parameters that describe the macauba forests. The research was carried out between January and August of 2016. Following the concept of toposequence, 6 hill slopes were studied where the macauba palm occurs spontaneously. The topsequences were delimited in 3 portions in the direction of the slope, descending from the top of the hill, through the half-slope, to the foot or lower third of the slope. In total, 18 sites were sampled (6 at the top, 6 at the half-slope and 6 at the foot), all of which were geo-referenced and had the total area calculated in hectares. The environmental characterization of the sites was carried out in the field, through the observation of several information, besides the description of the occurrence of other plant species. Soil samples were collected at each site for physical and chemical analysis for fertility purposes. In the native stands of macauba palm, phytosociological parameters were measured. Descriptive statistical analyzes were carried out using edaphic variables and phytosociological parameters in terms of mean and standard deviation. In the multivariate statistical analysis, Principal Component Analysis (PCA) and Canonical Correspondence Analysis (CCA) were performed to verify the associations between the soils and the phytosociological parameters of the macauba natural stands. The microbasin of the river Perdição, an area belonging to the municipality of Bambuí, has a source of spontaneous occurrence of macauba palm, with great productive potential. The palm occurs preferentially in medium and low landscape positions, in medium textured soils, originally covered by some savanna phytophysiognomy tipes. It has high plasticity as regards the physical-chemical characteristics of the soil and a certain tolerance to the aluminum soluble in the soil. The top, half-slope and slope portions of the relief do not differ in relation to the edaphic characteristics and the phytosociological parameters studied. Micronutrients contribute significantly to the association between soils and phytosociological parameters of macauba forests. Among the associations, Iron and Copper were positively correlated with height, at the same time as negatively with number of individuals / ha and Number of Coconut bunch / plant, in addition to the negative correlation between Boron and Number of Coconut bunch / plant. Therefore, there seems to be a close relationship between the spontaneous occurrence of macauba palm and the availability of micronutrients in the soil, which requires further studies.